Good question and thanks for raising the subject.  True, brushless motors come with many great advantages such as reduced power consumption, increased longevity, more compact design, and so much more.  However, they are still more expensive, by far, to produce.  Perhaps this will change in the futureAll things being equal, if brushless and brushed motors cost the same to build and implement, then yes, it seems like a good idea.  However, the economics don’t make that feasible at the moment.  For cordless tools with batteries it makes the most sense right now.  Batteries, by their nature, are limited in capacity for producing usable energy.  A corded product does not have that limitation.
 
Plus, we must also consider the function of the tool, how it is used, and if having a brushless motor brings a true benefit for the customer.  For example, for a tool like the CT Dust Extractor we offer in some countries an EC brushless version for special applications that require it.  This version is nearly 2.5 times more expensive compared to similar capacity units.  In this instance, these dust extractors meet different needs and have different designs, but this is just one example of the cost differentials when implementing such technologies.  Further, our current CT motors provide years of reliable service, are quite robust, and meet the needs of the extractors without additional costs.
 
The future will be sure to bring us many product improvements like efficiency, longevity, and performance increases across the board.  Yet even now we can enjoy many tools with the benefits of brushless technology.
 
Currently the tools available in North America that are equipped with brushless motors are:
 
C18 Cordless Drill
T18 Cordless Drill
PDC Cordless Hammer Drill
BHC Cordless Rotary Hammer
DWC Cordless Screw Gun
PSBC Carvex Jigsaw (cordless)
PSC Carvex Jigsaw (cordless)
PS Carvex Jigsaw (corded)
PSB Carvex Jigsaw (corded)
TSC Track Saw (cordless)
HKC Carpentry Saw(cordless)
ETS EC Sanders (3 models)
 
On a side note, Festool was one of the pioneers in bringing brushless motor technology to broader market application for portable power tools starting with the original C 12 in 2005.

I was actually astonished that Festool are releasing new products with brushed motors. Reducing cost has never seemed to be part of the Festool mantra and if you're designing a new tool why wouldn't you go brushless?

Thanks for the explanation @RustE

Using brushless tools with a bit of "lag" is like using a car with a turbo charger - you really do get used to it and pre-empt it so it doesn't slow down your work. At least that's what I find with my brushless tools (and with the Saab Turbos I had back in the 80s)

Brushless motors, or induction motors, operating on alternating current (AC) power sources are semi-synchronous.  This means that the motor operates at multiples or integer fractions of speeds that are synchronous with the frequency of the AC current powering the motor.  For 60-hertz AC power sources, the brushless motors operate at 3600 RPM (2-pole), 1800 RPM (4-pole), 1200 RPM (6-pole), and 900 RPM (8-pole).
 

Even though what is stated here about AC induction motors is correct, it is not applicable to BrushLess DC (BLDC) motors, and may cause some confusion. First off, the name. BLDC motors are not induction motors. The description above is correct for induction motors, but BLDC motors are permanent magnet 3-phase motors, and are neither induction, nor have a slip-speed. The rotor contains permanent magnets, and does not rely on induced magnetic fields in the rotor.

The speed of a BLDC motor is driven by a frequency, but that frequency is not the line-AC frequency. It is an artificially created frequency in the motor controller. There are no limits, per se, for this frequency, except for any mechanical limits on what the motor can spin.

.....one thing I've noticed with the other brushless drill drivers (Panasonic mostly) is that they have a split second worth of delay between pulling the trigger and something happening.

This delay is not a function of the motor or motor type, but of the soft-start nature of the PWM controller, as it is slowly ramping up power to get the motor to spin. As a matter of fact, it is typically more pronounced on non-BLDC motors because they lack the direct feedback at the winding-level. They can only see the external shaft RPM, which is less reliable at near-zero speed. The BLDC motor has internal sensors that tell the controller the exact rotational position of the rotor. (See below)

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Back to the original topic. BLDC motors are much more complex than brushed motors, and their respective controllers are more complex. The brushed motor PWM controller needs just a single power transistor for the output, and a single RPM sensor for feedback. The controller only needs to compare the set-speed with the feedback speed, which is a very simple circuit.

The BLDC motor, on the other hand, must include the added expense of the permanent magnets, plus at least 2 internal hall effect sensors to tell the controller the exact rotational position of the rotor.

The controller, instead of just 1 power transistor, it must have 6 power transistors. It doesn't just turn power on/off to the motor, but needs to artificially create a 3-phase, square wave, AC power to the motor from a DC supply. 3 transistors are required to control the 3 phases for positive voltage, and 3 more transistors to control the negative voltages.

The purpose of the brushes in a universal motor are for mechanical commutation (polarity reversal) for the windings. With a BLDC motor, this must be accomplished externally by the controller. This requires that the controller know the exact rotational position of the rotor (kind of like what the positions are on the hands of a clock). The controller uses the two sensors inside the motor to calculate the exact position, and it then uses this result to determine which of the 6 transistors must be turned on for that instant in time. And that isn't even to control the speed yet. That's just what's necessary to make the motor turn at any speed.

The speed control is a separate, but related circuit, which controls how often all this other switching is taking place based on the amount of power going into the transistors. Therefore, the controller for a BLDC motor is much more complex than a simple speed controller for a universal motor.

@Rick Christopherson Thanks for the BLDC motor information.  My coworker and I did not discuss DC motors, as we were talking about the HK 55 EQ having an universal AC motor.  The AC induction motor is in my Makita MAC700 air compressor.

I'm always curious as to the real advantages of a brushless motor for people like myself who regularly use the tools but not as part of my everyday work. It has never seemed like it really makes any difference in the actual results or, for that matter, on the life of the tool. For example, I don't remember ever replacing a sander or drill because the motor wore out. I have replaced brushes on more than one sander and on other tools but that isn't a big deal nor does it cost very much. I realize that this isn't the topic of this thread so sorry about that. I also understand that for those of you who use tools as professional builders, contractors, cabinetmakers, etc. the life of the tool may be affected. However for many of us, who make furniture, cabinets, and miscellaneous things out of wood, I have never felt that a brushless motor is worth any additional cost (if there is additional cost).

Even PLCs have boards of directors & shareholders.  It's a standard corporate model.  Unless of course it has sole proprietorship, which it doesn't.

Planned obsolescence is a basic, well documented and all but universally adopted tenet of capitalist entities.

Bottom line (just my opinion) : BL is better, it is the "best" choice for electric power tools. I understand it cost more to make but looking at Festool price tag, I expect it to be there, included. Just doesn't feel right buying a brushed-motor Kapex in 2017 just to name an example. I'm eyeballing a Kapex and a DTS sander but the motor type is kinda giving a sour taste to the deal (it's a big chunk of hard earned money).

Here's maybe something for you to think about, then. I had much of my kit stolen (I am a site carpenter and shop fitter - something between a framer and trim carpenter with a good dose of interior fitout thrown in for good measure) about 2 years ago and found myself facing the uphill struggle of replacing something like 60% (by value) of my fairly extensive tool kit. Very, very few corded tools by any manufacturer are offered in brushless form. In fact one of the few tools I can think of from the top of my head is the Mirka Deros sander. Why is this? The plain fact is that brushless tools cost more (if you don't believe me - check the differences in price point between brushed and brushless combi drills, circular saws and SDS drills for any of  the major cordless tool brands) and the saving in weight on corded tools is far less attractive than having a tool at 2/3 the price. Any contractor will tell you the same - and it's those guys who buy the tools in volume and who will need to be convinced of the advantages. For cordless that argument is pretty easy to make; brushless = less weight (on what is probably already a heavy tool) plus 40% longer run time and an increase in power (my Makita DHS680 saw is rated at over 600 watts vs. the DSS610 corded version at 350 watts) but where are  the same compelling arguments for most corded tools? I think you may be a very long time waiting for brushless everything

The motor usually has to come out, or at least be exposed, to replace brushes &/or carriers.  There's a couple of (maybe even 3) German manufacturers of vac motors that supply the entire German & Danish markets at least, meaning that you can get a "original" OEM type motor as a replacement for just about any well-known brand, variant, wattage your heart desires.  Many users will replace the whole motor assembly rather than just the brushes as there's little extra expense involved.  My Nilfisk/Alto/Wap/Festo vac had a motor replacement about 20 years ago.  My Kraenzle/Festo vac has just recently required new brushes.  Both were simple DIY jobs.

Kemo also make high quality, auto start/delay circuits capable of running high currents.  These cost about Euro 15 or so. This German firm has long been making OEM & aftermarket circuitry to industry.  I've also used one of these to turn a standard WAP Turbo XL vac into a Festo SR5E auto vac.

All this means that, once purchased, one will NEVER have to replace a good quality, well-built vacuum or dust extractor.  Ever, barring actual physical damage to the superstructure.  It helps that virtually all Euro tool manufacturers don't actually make Vacs &/or dust extractors themselves, relying instead on a mere handful of specialist manufacturers of machines & components.

Many users will replace the whole motor assembly rather than just the brushes as there's little extra expense involved. 

I don't get it. All brushes I ever replaced on power tools were 2 min $5 jobs. Replacing motor assembly will run into $100's and a serious PITA. What am I missing?

I don't know about the bigger Festool vacs, but on my Mini the brushes are easily replaced BUT you have to take the entire housing of the vac apart. It's a simple screw/unscrew job, but it takes time. Given how Festool repair service can easily charge you €70 per hour, one can understand where the extra cost comes from.

Marketing sure is a powerfull thing..... for some battery powered tools the advantages can be worth the price difference. For the rest not so much.

Most corded tools are plenty powerfull and maintanance is hardly an issue, brusless or not.

If economics are the reason that Festool chooses not to use brushless motors in their cordless tools, how do you explain other companies like Makita and Milwaukee using brushless in a much wider variety of tools and selling them for less than Festool? 

@acknowlli - The ETS EC is a corded brushless motor and so is the Planex Easy.

Quote from the Festool USA website:
The new ETS EC 150 EQ is perfectly built for manual operation to reduce fatigue when carrying out overhead sanding work and a good feeling on edges, as well as convenient operation in any position. This sander is only 4 1/2" (116 mm) high, contains a brushless EC-TEC motor, and ergonomic housing geometry with perfectly balanced center of gravity. This sander also comes with additional innovative details such as automatic dust control, integrated sanding pad brake, and the unique Vibration Control System for added health benefits.

Agreed, the Planex has the power supply/motor combination because here it makes sense for improved weight distribution (away from the head). EC makes sense here because of the dustproof design.

Regarding Mirka, yes, as I said they are slowly figuring it out. The brushless sanders had external power supplies for many years. They start getting rid of those now.

Another benefit of BL DC is high torque at low speeds. That makes sense in sanders, because the addet weight from the power supply gets compensated, because you don't need a mechanical gearbox any more.

Brushless has nothing to do with hi/lo current. hi/lo voltage.   

Brushless requires a controller, that is the difference.  It's an added cost, an if there isn't a need for it, they are not going to do it.

You design a motor for the need, if you need high torque, it will have high current draws.  Battery tools keep going to higher voltages so they can have more power without more amps.  Corded tools have never had much option, the voltage is either 120 or 230/240VAC.

There is a fundamental difference in performance between brushed and brushless motors. The brushless motor is an induction motor so if it is overloaded, by being pushed too hard, it will drop out of sync and stall.

On the other hand a brushed motor will simply draw more current and keep going, for a short time untill it overheats and burns out.

This means that, for the same user performance, a brushless motor needs to be nearly twice the wattage rating.

This doesn't mean that a BL motor will use more power. Both motors will use roughly the same power for the same job but the B motor can easily exceed its rating if required. In battery tools a BL is more efficient, and has more torque at low speed, so the battery lasts longer.

Comparing the wattage rating between B and BL motors will not give you any indication of how they will perform in a power tool in actual use.

To prevent burnout on brushed motors manufacturers fit temp sensors which, like on the TS55, shut them down until they cool down.

Brushless requires a controller, that is the difference.  It's an added cost, an if there isn't a need for it, they are not going to do it.

There is a need for it because people want it. People want quiter motors that are more controllable and run smoother. Added cost? Hmm, not sure about that. Pretty sure that controller will soon be on a single chip costing 50 cents. Of course it costs a bit more now it is still new.

I remember how I bought my first hard disk drive back in 1997. Quantum Fireball 6,4 GB, top of the line back then. Paid €200 for it. Now you can buy a 2TB SSD for only €134. It has 300 times the capacity, 1/100th the size, and works about 80-100 times faster.

  Corded tools have never had much option, the voltage is either 120 or 230/240VAC.

Not much option? My smallest 220 volt tool draws 80 watts, my biggest 2600. Try that with your 36v batteries.

Water cooled drills and cutters use an isolation transformer, so that the 230V coming out of it isn't referenced to ground, but floating. That prevents electric shock when touching a live wire while standing on conductive ground.
 
The low voltage DC power supply Mirka used for their Ceros sanders is an entirely different animal.

Cheese, you can wet sand at any level you want. When you get in the higher grits, the change is not as big as in the lower grits. The difference between 120 and 240 is bigger than between 400 and 800.

In the body shop we had a rack full of the black waterproof 3M paper, it ranged something like 400, 600, 800, 1200, 1600, 2000. Can't remember exactly anymore, that was around 40 years ago, but we had a lot of grits to choose from.